Manufacture of photographic film



106- COMPOSITIONS, g i'el. .Qbfi W937 13 UNITED STATES Cross Reference PATENT oFFIcE MANUFACTURE OF PHOTOGRAPBIC FILM Gale F. Nadeau, Rochester, N. Y., assignor to Eastman Kodak Company, Jersey City, N. J., a

corporation of New Jersey No Drawing.

Application December 24, 1934, Serial No. 758,988

14 Claims. (01. 91-89) This invention relates to the manufacture of photographic materials, and more particularly to the preparation of gelatin subbing solutions in which the gelatin is dispersed therein by means of various easily decomposable organic acids.

In the manufacture of photographic film it is necessary to deposit on the usual cellulose derivative support or film base an extremely thin coating of gelatin in order to prepare the surface of the material for the permanent adhesion of the light-sensitive emulsion theret'o. It is known that the keeping qualities and other properties of the finished film are dependent to a very great ex- .tent upon the nature of the gel sub and the manvenient or expensive. For example, the use of volatile acids has been suggested, but it is found that they are disadvantageous because of the fact that they volatilize during the subbing operation and corrode the film making machinery and the solvent recovery system which is customarilya part thereof. In order to overcome this difllculty it has been proposed to use certain nonvolatile acids, but the use of such agents has the serious disadvantage that the acid remains in the gel sub and exerts a destructive or desensitizing action on the sensitive emulsion.

. The present invention has as an object to overcome the above-mentioned prior art difficulties and to provide a method of dispersing gelatin in a subbing solution by means of dispersing agents which will not corrode the fihn making machinery or solvent recovery system connected therewith and which will not remain as such in the support and contaminate or desensitize the photographic emulsion. Another object is to provide a non-volatile and easily decomposable agent for dispersing gelatin in a solution or dispersion thereof. A further object is to provide a new type of gel solution in which the gelatin is dis-'- persed by means of a non-volatile, non-corrosive dispersing agent which has no adverse effect upon photographic emulsions. Other objects will appear hereinafter.

These objects are accomplished by the following invention which, in its broader aspects, comprises the use asdispersing agents in gel subbing solutions of various aliphatic or aromatic organic acids which, although stable at ordinary room temperatures, are, nevertheless, easily decomposable into volatile or non-volatile, non-corrosive compounds at the temperatures generally employed in the manufacture and subbing of photographic film support. Among these acids may be mentioned the beta-ketonic acids, such as benzoyl acetic, methyl acetoacetic, and trimethyl acetoacetic, as well as nitro-acetic acid. I have found that these acids are excellent dispersing agents for gelatin and yet are decomposable at moderately high temperatures, that is, 180-260 F., the decompositions in each case being represented by the following equations:

(1) OQHIOO-OHQOOOH C6HDO0.0HI+O0I Benroyl acetic acid acetophenonc (2) (OHdnQOODHgCOOH (0Ha)|.OO0-OH|+CO| Trimethyl ecetoacetic acid pinacolone (3) OH;O0.0H(OH|)OOOH OHpCOOfliH-CO: Methyl acetoacetic methyl ethyl ketone EXAMINER In the following examples and descriptions; I

I have set forth several of the preferred embodiments of my invention, but they are included merely for purposes of illustration and not as a limitation thereof.

My invention may be conveniently illustrated by the subbing of a cellulose acetate support. For this purpose I make up a gel subbing solution as follows:

. 5 Per cent A. Gelatine 1.0 Benzoylacetic acid 2.0 Water 4.0 Acetone 65.0 Methanol 28.0

This solution is applied to the cellulose acetate support in any convenient manner, such as by beading, immersion, roll application, or otherwise, the subbing operation preferably being carried out in, connection with, or as a part of, the process of making the film support itself. It is found that a subbing solution made as above described is a clear water-white liquid in which the gelatin is completely dispersed. After the application of the subbing solution to the film support, the support is subjected to a temperature of about laid down on the film, has no desensitizing or other adverse action on the emulsion which is subsequently applied to the film. After the subbing operationis completed, the subbed support is coated with the light-sensitive emulsion in the usual manner.

Other gelatin solutions suitable for the subbing of cellulose acetate and other types of cellulose derivative supports are as follows:

While I have found it convenient to illustrate my invention by reference to gelatin solutions suitable for the subbing of cellulose acetate film support, my invention is in no sense limited to the subbing of this particular type of support,

as it may be applied with equal success to the treatment of almost any type of cellulose derivative material, providing the necessary adjustments in the proportion and kind of solvent constituents used in the subbing solution are made. As is well known to those skilled in the art, each different type of cellulose derivative, in general.

requires a slightly different solvent combination. It may be pointed out at this point that the gel subbing solution is of a somewhat difierent nature than a gelatin emulsion, in that it must contain components that have a solvent or at least a softening or swelling action on the cellulose derivative material of the support, that is, these solvent components must wet and bite in the cellulose derivative, as otherwise it would be impossible to anchor or stick the gelatin to the support. These solvent components comprise a wide range of solvents, typical examples being acetone, methyl alcohol, ethyl alcohol, methyl cellosolve and others.

It will be evident that my invention has completely solved the extremely troublesome problem of obtaining the necessary degree of dis persion of the gelatin in the subbing solution without the deleterious efiects heretofore resulting from the use of corrosive volatile acids, or noncorrosive, non-volatile acids which adversely affect the sensitivity of the emulsion subsequently applied to the film. This is due to the fact that the acids which I employ as dispersing agents for the gelatin are immediately decomposed at moderately high temperatures into compounds which are entirely non-corrosive and, either do not remain in the film at all, or if they do remain, are entirely free from any adverse effect upon the light-sensitive materials.

These acids offer a further decided advantage in that their use as dispersing agents as herein described eliminates that defect common to photographic films known as sub lines. These are lines or streaks produced to a great extent by particles of gelatin which precipitate from the subbing solution due to insufficient dispersion of the gelatin, and, since these particles contain more acid than the rest of the support, they act to desensitize the emulsion wherever they contact with it. It was heretofore extremely difiicult, ii. not impossible, to prevent a certain amount of precipitation of the gelatin because of the fact that, due to the undesirable properties of the dispersing agent, the amount of agent added had to be kept down to the barest minimum with the result that the gelatin was often insufiiciently dispersed in the subbing solution and a certain amount of precipitation was bound to occur. As contrasted with this prior practice of using a minimum amount of dispersing agent, in accordance with my invention any amount of the above mentioned acids necessary to keep the gelatin fully dispersed may be employed without fear of adverse effects, due to the fact that these substances are immediately decomposed into harmless products immediately after the subbing operation. One may even use an execs of the dispersing agent and thus be assured of producing a stable and highly dispersed gelatin subbing solution which will not precipitate gelatin nor produce the above mentioned sub lines. I

By the term sub as used herein, I refer to an extremely thin layer which is deposited on the surface of a cellulose derivative film support for any purpose, but more particularly to serve as an undercoat for the application of a layer of photographic emulsion or other material. By the term subbing," I refer to the operation of depositing of such a layer from an appropriate subbing solution. A subbing solution is, of course, a solution which is suitable for the deposition of such layers.

While my invention is best illustrated by reference to the preparation of gelatin solutions suitable for the subbing of photo aph c film supports, it is not to be understood as limited to this particular application, as in its broader aspects it includes the preparation of gelatin solutions in general in which the gelatin is dispersed in the solvent by means of the acids described herein.

What I claim as new and desire to secure by Letters Patent is:

1. A gelatin solution suitable for the subbin of photographic film support which comprises gelatin dispersed in a solvent by means of an organic acid decomposable into volatile or nonvolatile, non-corrosive compounds at temperatures of -260 F. I

2. A gelatin solution suitable for the subbing of photographic film support which comprises gelatin dispersed in a solvent by means of an acid selected from the group consisting of benzoyl acetic acid, methyl acetoacetic acid, trimethyl acetoacetic acid, and nltroacetic acid.

3. A gelatin solution suitable for the subbing of cellulose derivative photographic film support which comprises gelatin dispersed in a solvent by means of a beta ketonic acid decomposable into a ketone and carbon dioxide at temperatures of 180-260 F.

4. A gelatin solution suitable for the subbing of photographic film support which comprises gelatin dispersed in a solvent by means of benzoyl acetic acid.

5. A gelatin solution suitable 'for the subbing of photographic film support which comprises gelatin dispersed in a solvent by means of methyl acetoacetic acid.

6. A gelatin solution suitable for the subbing of photographic film support which comprises gelatin dispersed in a solvent by means of trimethyl acetoacetic acid.

7. A gelatin solution suitable for the subbing of cellulose derivative photographic film support which comprises gelatin dispersed in a mixture of acetone, methyl alcohol and water by means of IUD. UUIVHUN HUND,

- which comprises gelatin dissolved in a mixture of COATING 0R PLASTIC an acid selected from the .group consisting oi! benzoyl acetic acid, methyl acetoacetic acid, trimethyl acetoacetic acid and nitroacetic acid.

8. A gelatin solution suitable for the subbing ot a. cellulose acetate photographic film support a which comprises gelatin dissolved in a mixture of acetone, methyl alcohol and water by means of methyl acetoacetic acid.

11. The method or subbing a photographic film support which comprises applying thereto a gelatin solution in which the gelatin is dispersed by means ofa dispersing agent selected from the group consisting of benzoyl acetic acid, methyl acetoacetic acid, trimethyl acetoacetic acid and nitroacetic acid, subjecting the film to a temperature oi. 180-260 F., whereby the solvents and volatile constituents are removed from the deposited layer and the dispersing agent is decomposed into volatile or non-volatile, non-corrosive compounds.

Cross iieierence 12. The method of subbing a photographic film support which comprises applying thereto a gelathe solvents and volatile constituents are removed from the deposited layer and said acid is decomposed into volatile or non-volatile, non- I corrosive compounds.

13. The method oi subbing a photographic film support which comprises applying thereto a gelatin'solution in which the gelatin is dispersed by means of methyl acetoacetic acid, subjecting the film to atemperature 0! about ISO-260 R, whereby the solvents and volatile constituents are removed from the deposited layer and said acid is decomposed into volatile or non-volatile noncorrosive compounds.

14. The method of subbing a photographic film support which comprises applying thereto a gelatin solution in which the gelatin is dispersed by means of trimethyl acetoacetic acid, subjecting the film to a temperature of about 180-260'F., whereby the solvents and volatile constituents are removed from the deposited layer and said acid is decomposed into volatile or non-volatile, non-corrosive compounds.

GALE ENADEAU.

LN-HVIIWLH 

